Moths Bright Underwings Startle Predators

Catocala moths are among the largest and showiest of North American moths. These moths are widely known by the common name "underwings." The name underwing is very descriptive. In general, underwing moths appear much as any other moth with nondescript brown or gray mottled forewings.

Unlike most moths, the hindwings, or underwings, of Catocala are brightly colored. The scientific name Catocala literally means beautiful below. Frequently the hindwings are striped with black bands alternating with orange or red bands. Since the underwing moths, like most other moths, are night-flying insects, the bright colors are not often seen, except when the insect is displayed in a collection.

While not often visible, the colored wings of the underwing moths have an important biological function. Underwing moths are subject to predation by birds. As a first line of defense, the moth uses the cryptic coloration of the forewings to blend into the environment, specifically the bark of a tree on which it rests during the daylight hours.

It is generally assumed that the brightly colored underwings serve to frighten predators if the insect is discovered. The sudden display of bright colors results in a startle response by birds and might provide an opportunity for the moth to escape becoming a meal. It is also possible that the colors serve a deflective function, causing the bird to direct its pecking to the hindwings rather than the biologically more-important body of the insect.

The striking contrast between the forewings and the hindwings of these moths fascinates most viewers. But Theodore Sargent in his book "Legion of Night the Underwing Moths" states that the common names of the moths are at least as intriguing as their beauty. Moths are frequently associated with night, mystery and death, so we have the Dejected Underwing and the Inconsolable Underwing. We also have the Mourning Underwing and the Foresaken Underwing.

Also in the sad vein is the Widow Underwing. Other names relate to love and marriage, such as the Betrothed Underwing, the Consort Underwing and the Mother Underwing. We also have the Sweetheart Underwing and the Bride Underwing, which should not be confused with the Old Maid Underwing.

Nearly all of the older Catocala names are female names from the Bible, Shakespeare, Russian folklore and Greek mythology. From Roman history we find virtuous women such as Irene and the not-so-virtuous, such as Delilah and Cleopatra.

Why so many references to female names in this group of insects? It just might be that the men who described each beautiful and mysterious moth were reminded of some of their female acquaintances of the human species.